Spiral drill having unequal cutting faces

ABSTRACT

A tool for cutting certain extremely hard materials, such as the aluminum bronzes, which consists of a working end having a plurality of cutting faces, all of which are disposed substantially parallel to the longitudinal axis of the tool. Cutting edges, along the forward ends of the cutting faces, are all disposed at approximately the same angle to the longitudinal axis of the tool. A clearance surface is rearwardly disposed at an angle of approximately 45* from each of the cutting faces.

United States Patent Simonffy 1451' mpsalglt liw [54] SPIRAL DRILL HAVING UNEQUAL OTHER PUBLICATIONS I CUTTING FACES Hinman, Practical Designs for Drilling Milling and [72] Inventor: Louis Simontfy, 7253 West Tapping Tools, 1946, page 273, Fig. 261.

Lafayette, Detroit, Mich. 48209 Primary Examiner-Gil Weidenfeld [22] Flled July 1970 Attorney-Adolph G. Martin [21] App]. No.: 59,243

[57] ABSTRACT [52] us. Cl ..40s/22s, 408/230 A tool for Cutting main extremely hard materials 51 int. Cl. ..B23b 51/02 Such as the aluminum bmnzes which mists 0f 8 of Search working end'having a plurality Of cutting faces, all Of 408/230. 29/103 A which are disposed substantially parallel to the longitudinal axis of the tool. Cutting edges, along the forward ends of the cutting faces, are all disposed at ap- [56] Reerences cued proximately the same angle to the longitudinal axis of UNITED STATES PATENTS 1 v the tool. A clearance surface is rearwardly disposed at an angle of approximately 45 from each of the cutting 2,936,658 5/1960 Riley ..408/230 faces. 1,320,985 ll/l9l9 Brightman ..408/230 984,323 2/1911 Vauclain ..408/230 1 Claim, 7 Drawing Figures PATENTEDnEc 19 I972 FIG.6

INVENTOR LOUIS SIMONFFY syfl wv y ATTORNEY SPIRAL DRILL HAVING UNEQUAL CUTTING FACES BACKGROUND OF THE INVENTION This invention relates generally to cutting tools, but more particularly to tools for use in working the aluminum bronzes. There are many known materials, such as aluminum bronze, which possess highly desirable physical properties, but which have had very limited use because of the problems encountered in drilling and working these materials.

In drilling this extremely hard material, the conventional tools tend to bind, overheat and beak despite the use of lubricants, coolants and cutting compounds. Fully cognizant of this situation, the applicant has designed and developed a plurality of cutting tools, especially adapted for use in working aluminum bronzes, the basic principle of which is applicable to drills, counter-bores, center-drills, counter-sinks, and other related tools.

SUMMARY OF THE INVENTION This invention consists of an elongated body having a working end with a plurality of cutting faces substantially parallel to the longitudinal axis of the body. Cutting edges, along the forward ends of the cutting faces, are all disposed at substantially the same angle to the longitudinal axis of the body. A clearance surface, adjacent each of the cutting edges, is rearwardly disposed therefrom at at an angle of approximately 45 to the cutting face.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation view of a drill embodying the applicants invention, showing the two cutting faces 16 and 18, and the relative depth of each.

FIG. 2 is an elevation view of the working end 14 of the drill 10, taken substantially on plane 2--2 in FIG. 1, showing one of the cutting faces 16 and the rearwardly disposed clearance surface 26.

FIG. 3 is a plan view of the working end 14 of the drill 12, taken substantially on plane 3-3 in FIG. 2, showing the two cutting edges 22 and 24.

FIG. 4 is an elevation view of a counter-bore 40 embodying the applicants invention, showing the three cutting faces 46,48 and 50, and the clearance surfaces 60.

FIG. 5 is a plan view of the working end of the counter-bore 40, taken substantially on plane 5-5 in FIG. 4, showing the three cutting edges 54,56 and 58.

FIG. 6 shows a counter-sink 70 embodying the applicants invention, showing one of the four cutting faces 76 and the clearance surfaces 84.

FIG. 7 is a plan view, taken substantially on plane 7--7 in FIG. 6, showing the four cutting edges 80.

CONSTRUCTION For a more detailed description of the invention, reference is made to FIGS. 1,2 and 3 of the drawing in which numeral 10 designates a drill with an elongated fluted body 12 having thereon a working end 14. A pair of cutting faces 16 and 18, on the working end 14 of the drill, are disposed approximately parallel to the longitudinal axis of the elongated flutedbody 12.

The forward and back sides of the cutting faces 16 and 18 are substantially parallel to each other, and the depth 21 of one cutting face 16 is approximately twice that of the other cutting face 18. Optimum cutting results are achieved when the depth of the larger cutting face 16 is approximately 0.040 inches, andlthat of the smaller cutting face 18 is approximately 0.020 inches. However, satisfactory results are obtained with the depth of the larger cutting face 16 ranging from 0.020 inches to 0.060 inches, and that of the smaller cutting face 18 ranging from 0.005 inches to 0.035 inches.

Cutting edges 22 and 24, on the forwardend of each of the cutting faces 16 and 18 respectively, are disposed to the longitudinal axis 20 of the elongated body 12 at an acute angle 25, the magnitude of which will depend upon the pitch of the fluting in the body 12. A clearance surface 26, adjacent each of the cutting edges 22 and 24, is rearwardly disposed therefrom on an angle 28 of approximately 45 to the cutting faces 16 and 18 respectively. 4

Referring to FIGS. 4 and 5 of the drawing, numeral 40 designates a counterbore with an elongated fluted body 42 having thereon a working end 44. Three cutting faces 46,48 and 50, on the working end 44 of the counter-bore 40 are disposed approximately parallel to the longitudinal axis 52 of the elongated fluted body 42.

Cutting edges 54,56 and 58, on the forward end of each of the cutting faces 46,48 and 50 respectively, are disposed at substantially right angles to the longitudinal axis 52 of the elongated body 42. A clearance surface 60, adjacent each of the cutting edges 54,56 and 58, is rearwardly disposed therefrom an an angle 62 of approximately 45 to the cutting faces 46,48 and 50 respectively. A customary pilot end 64, of reduced diameter, is provided on the forward end of the counter-bore 40.

Referring to FIGS. 6 and 7 of the drawing, numeral designates a countersink with an elongated body 72 havingan enlarged working end 74. Four cutting faces 76, on the enlarged working end 74 of the counter-sink 70, are disposed approximately parallel to the longitudinal axis 78 of the elongated body 72.

Cutting edges 80, on the forward end of each of the four cutting faces 76, are disposed to the longitudinal axis 78 of the elongated body 72 at the customary acute angle 82. A clearance surface 84, adjacent each of the cutting edges 80, is rearwardly disposed therefrom at an angle 86 of approximately 45 degrees to the cutting face 76.

The preceding discussion completes a description of the structural details of the applicants invention herein disclosed. However, to facilitate a more thorough and comprehensive understanding of the subject matter, a discussion is immediately hereinafter directed to the manner in which the tools operate to accomplish and perform their intended function.

USE AND OPERATION Since the applicants counter-bore and counter-sink, disclosed in FIGS. 4 through 7, function in the ordinary manner well known in the art, no detailed explanation will be herein directed to their use and operation. However, as the applicants drill functions in an unusual manner to accomplish its results, a brief description of the way in which the tool operates is immediately hereinafter set forth.

In use, when a downward force is applied to the applicants drill so as to cut into a work piece, a lateral thrust is generated against the two cutting faces 16 and 18. Since one of the cutting faces 18 is approximately half the size of the other cutting face 16, the total lateral thrust against the larger cutting face 16 is substantially twice that on the smaller cutting face 18.

This differential in lateral thrust, during the cutting operation, forces the longitudinal axis 20 of the drill 10 to travel in a small circular orbit concentric to the hole being drilled. This concentric travel permits the drill 10 to cut a slightly over-size hole, which automatically provides the clearance necessary to prevent binding and consequent breakage of the drill 10.

In practice, speeds varying from40 to 120 rpm. provide clearances up to a maximum of approximately 0.004 inches, for drills ranging in size up to five-sixteenths inch in diameter, when working the moderately hard aluminum bronzes. For drills over five-sixteenth inch in diameter, the cutting speeds must be held between 40 and 90 r.p.m'. to provide substantially the same clearances.

However, maximum clearances of approximately 0.006 inch and 0.002 inch are produced in the course of working the softer and harder aluminum bronzes respectively, at such indicated drill speeds. Drill speeds, in excess of those above set forth, will produce proportionately larger clearances, in the holes being drilled, than the previously indicated maximums.

The use of lubricants and coolants, with the applicants drill, will extend the life span of the tool, and likewise reduce maintenance costs involved in resharpening the drill. The applicants tool was designed and intended especially for use with the aluminum bronzes, and it has accordingly not proven satisfactory for use in working softer materials such as copper and brass.

Based upon the foregoing discussion, the applicant is of the opinion that his invention has fulfilled a long-felt need in the field of cutting tools, and that he has accordingly made a valuable contribution to the related art. However, while the invention was described with reference to the structural details of a limited number of embodiments, it will be appreciated by those familiar with the art that the principles involved are susceptible of numerous other practical adaptations.

I therefore claim as new, and desire to secure by Letters Patent:

1. A cutting tool comprising anelongated body with a working end having thereon at least two'cutting faces substantially parallel to the longitudinal axis of the elongated body, a cutting edge on the forward end of each of the cutting faces, such cutting edges all being disposed to the longitudinal axis of the tool at substantially the same angle, and a clearance surface adjacent the cutting edges and rearwardly disposed therefrom at an angle of approximately 45 degrees to the cutting face, such elongated body having therein spiral fluting and one of the cutting faces having a depth approximately twice that of the other cutting face so that the greater thrust developed against the larger cutting face during a drilling operation forces the tool to move in the direction of such reater thrus t so that the longitudrnal axis of the drill ravels In a circular orbit concen- 

1. A cutting tool comprising an elongated body with a working end having thereon at least two cutting faces substantially parallel to the longitudinal axis of the elongated body, a cutting edge on the forward end of each of the cutting faces, such cutting edges all being disposed to the longitudinal axis of the tool at substantially the same angle, and a clearance surface adjacent the cutting edges and rearwardly disposed therefrom at an angle of approximately 45 degrees to the cutting face, such elongated body having therein spiral fluting and one of the cutting faces having a depth approximately twice that of the other cutting face so that the greater thrust developed against the larger cutting face during a drilling operation forces the tool to move in the direction of such greater thrust so that the longitudinal axis of the drill travels in a circular orbit concentric to the hole being cut thereby automatically providing the clearance necessary to prevent the drill from binding and breaking. 